They are only blue if they eat chow. If you feed them silkworm chow, they turn green and won't turn blue again. I have found that chow fed take longer to grow and are significantly weaker but I also noticed that lizards prefer the green ones. They will turn green from any green food. I have 40 now that I'm putting into my breeding colony so I've been offering them all different types of food and no two are alike. It's pretty insane to see all the color and pattern combos.